1. Field of the Invention
This invention relates to an image forming apparatus realized, for example, as an MFP (Multi-Function Product/Printer/Peripheral), and to an image processing apparatus used therein.
2. Description of the Related Art
An MFP is an image forming apparatus provided with a plurality of functions such as functions of a printer, scanner, fax machine, in addition to a photocopier function. Such apparatuses appeared because, by sharing an image formation portion and a scanner portion, advantages such as reduced costs and smaller installed space became possible. Hence as the memory installed in such apparatuses, low-cost memory having small capacity to the extent possible is desired. However, performance declines if the memory capacity allocated to each function is small.
In particular, during use as a photocopier, large memory capacity is required in an aggregation mode, a sorting mode not using a sorter, a booklet mode, and a mode in which a plurality of copies of a plurality of pages are created. This is because in these modes, jobs are executed in a state in which data for a plurality of pages, which is image data for document images of a plurality of pages, is stored in memory.
An aggregation mode is a mode in which the document images of a plurality of pages are aggregated on a single recording sheet and output.
A sorting mode is a mode in which, when a plurality of copies of document images of a plurality of pages are created, output is performed in a state in which the pages are arranged in each copy. Of such modes, a sorting mode not using a sorter is a mode in which, rather than using a sorter to sort the sheets on which are formed images of pages for each copy, each copy is output, with pages arranged, from the image forming apparatus. For example, when making three copies of a first through a third page, output of a sheet on which is formed the image of the first page, a sheet on which is formed the image of the second page, and a sheet on which is formed the image of the third page, is repeated three times.
A booklet mode is a mode in which a plurality of sheets on which are formed images are formed into a booklet and output.
A mode in which a plurality of copies of a plurality of pages are created is a mode in which the document images of a plurality of pages are read, and a plurality of copies of sheets on which are formed the image for each page are created (preset plurality mode). For example, when making three copies of a first through a third page, output of a sheet on which is formed on the image of the first page is repeated three times, then output of a sheet on which is formed the image of the second page is repeated three times, and then output of a sheet on which is formed the image of the third page is repeated three times.
In an aggregation mode and other modes the memory capacity increases, and so the following image forming apparatus has been proposed. This image forming apparatus has a page memory which comprises a work memory area for electronic sorting which stores bit images, and a file memory area which stores compressed images. This image forming apparatus dynamically sets the file memory area and work memory area according to whether the binarization processing mode of input images is a character mode or a photo mode. By this means, page memory is utilized effectively, and the number of stored pages for electronic sorting can be increased using small memory capacity.
In recent years, even MFPs which are monochrome apparatuses are equipped with full-color scanners, and are capable of saving multivalued data. That is, two CODECs, which are a coding/decoding device (CODEC) which is designed to save multivalued data, and a coding/decoding device (CODEC) which is designed to save binary or four-valued data, are equipped by default. However, even when a monochrome apparatus has a full-color scanner, copy functions store only a preset number of images in memory, or store in memory only the necessary images for jam recovery by an automated document conveyor device. Consequently a monochrome apparatus is not equipped with large-scale memory as in color apparatuses. Hence an increase in the number of stored images using small memory capacity is sought.
However, the above image forming apparatus merely modifies the boundary of memory areas according to the processing format for input data, and does not reduce the quantity of data itself. Hence the efficiency of memory use is improved, but there are limits to increases in the number of stored images.